Last week, the Royal College of Veterinary Surgeons ruled that James Main, the Lambourn vet who injected one of Nicky Henderson's horses with a banned substance a few hours before a race at Huntingdon in February 2009, should be struck off their register having been found guilty of "disgraceful" professional conduct. With Henderson having concluded his own three-month ban from making entries over the same case as long ago as the autumn of 2009, many in racing will hope that a final line has been drawn under one of the grubbier affairs of recent years.

Henderson most certainly will. While Main, who has another three weeks to lodge an appeal, faces an uncertain future, stripped of the right to earn his living as a vet, March 2011 has the potential to be one of the most memorable months of Henderson's career. He is odds-on with Hill's to record the four victories at the Cheltenham Festival that would make him the most successful trainer in the meeting's history and, in Long Run, he appears to have finally uncovered a serious contender for the Gold Cup.

Yet this disparity in the subsequent and current fortunes of Main, who administered the injection of a clotting agent called tranexamic acid, and Henderson, the valued client who ordered him to do so, is just one of several troubling aspects of the case that remain unresolved.

Among the more obvious questions that still require an answer is how many other horses, at Henderson's yard and elsewhere in Lambourn, were getting the same injections on race days under the guise of a "pre-race check", as Main would describe it in his practice records. In other words, how many more trainers at jumping's HQ were – and so probably still are – more than willing to treat the anti-doping rules with contempt if they think they can get away with it?

Henderson himself seemed to suggest at his British Horseracing Authority disciplinary hearing that race-day injections of TA were very rare at his yard. Yet Main's evidence to the Royal College of Veterinary Surgeons (RCVS) implied that it was common practice, indeed almost routine, over a number of years for horses believed to be at risk of bleeding.

Henderson, meanwhile, told the RCVS that "plenty of trainers" were also using TA at the time, "because of the amount of trainers who came up to me after the case and said, 'I'm not using it any more,'"

This alone should really be enough to persuade the BHA to re-interview Henderson about the wholeaffair, to see if there is anything that he would like to add to his originalaccount. If there is a belief loosein a major training centre that a section of the rules with such fundamental importance for the sport's integrity only matters if you get caught, the Authority needs to stamp it out.

Whether the BHA is minded to take this any further is another matter, though the Authority is currently studying a transcript of the RCVS hearing and will announce its decision in due course.

But if it does feel a re-interview is necessary, it might also give Henderson a chance to express some genuine regret for the whole affair and his own role at the centre of it, something that he has seemed to find difficult thus far. Instead, he has seemed more concerned about the use of the word "doping" in connection with Moonlit Path, even though the regulations involved are widely, and fairly, described as the "anti-doping rules".

Brilliant trainer though he undoubtedly is, and will remain, Henderson ordered a vet to do something that, it became clear at the RCVS hearing, even the yard's pupil assistant knew was a breach of those rules.

But while the vet's career is quite possibly in ruins, Henderson marches on towards greater glory. This has been a messy, disturbing case from the outset and even now, two years on, it does not feel as though it has reached a satisfactory conclusion.